Interchangeability of two Enterovirus 71 inactivated vaccines in Chinese children: A phase IV, open-label, and randomized controlled trial

Targeting 7-dehydrocholesterol reductase against EV-A71 replication by upregulating interferon response

Recent studies have shown a close link between viral infections and cholesterol metabolism. Here, we reported that 7-dehydrocholesterol reductase (DHCR7), a terminal enzyme for catalyzing cholesterol synthesis in the Kandutsch-Russell pathway, is harnessed by enterovirus A71 (EV-A71) benefitting for its replication. Overexpression of DHCR7 resulted in upregulating of EV-A71 replication, while the S14A mutation, which reduces DHCR7 enzyme activity, has no effect on EV-A71 replication. Knockdown of DHCR7 expression with small interfering RNA (siRNA) or enzyme activity inhibition with pharmacological inhibitor AY9944 could significantly inhibit EV-A71 replication. Adding cholesterol to DHCR7 knockdown cells or AY9944-treated cells could rescue EV-A71 replication. More importantly, prophylactic administration of AY9944 effectively protected mice from lethal EV-A71 infection. In addition, the natural cholesterol precursor 7-dehydrocholesterol (7-DHC), which is converted to cholesterol by DHCR7, has a similar effect against EV-A71 infection. Mechanistically, AY9944 or 7-DHC treatment can specifically promote IRF3 phosphorylation to activate interferon response. Moreover, AY9944 effectively cleared coxsackievirus B3 (CVB3) and coxsackievirus A16 (CVA16) infections in vitro. In conclusion, pharmacological modulation of DHCR7 might provide a chance for treatment of enterovirus infection, including EV-A71.

Clinical evaluation of the lot-to-lot consistency of an enterovirus 71 vaccine in a commercial-scale phase IV clinical trial

OBJECTIVE

To evaluate the immunogenicity, safety and lot-to-lot consistency of an inactivated enterovirus 71 (EV71) vaccine cultured in bioreactors with different specifications after full immunization.

METHODS

A randomized, double-blind trial was performed in 3,000 children aged 6 ~ 35 months with six vaccine batches, which were prepared in 40 L and 150 L bioreactors for three consecutive batches respectively. Children were immunized on day 0 and 28, serum samples were collected on day 0 and 56, and neutralizing antibody titers were determined by the microcytopathic method. Immediate reactions were recorded within 30 min, local and systemic symptoms were recorded within 0 ~ 28 days, and serious adverse events were recorded within 6 months.

RESULTS

After immunization with two doses of the inactivated EV71 vaccine, the neutralizing antibody GMT was 825.52 ± 4.09, and the positive conversion rate was 96.18%, with no significant difference. The 95% CI of the serum neutralizing antibody GMT ratio between the two groups after immunization with the three vaccine batches produced in the 150 L and 40 L bioreactors ranged from .67 ~ 1.5. The overall incidence of adverse reactions, mainly grade 1 reactions, for all 6 batches from 0 to 28 days after vaccination was 49.62%, with no significant difference (p = .8736). The incidence of systemic adverse reactions, primarily fever and diarrhea, was 45.14%; the incidence of local adverse reactions, primarily erythema and tenderness, was 9.43%.

CONCLUSION

The EV71 vaccine was highly immunogenic and safe in children aged 6-35 months, and 6 consecutive batches produced by the two bioreactors with different specifications were consistent.

Separation and purification of highly infectious enterovirus A71 particles using a strong anion-exchange column

Virions produced from cell culture is the primary source for production of formalin-inactivated whole virus vaccines for enteroviruses. EV-A71 particles produced from culture system comprise two major types, the immature/empty (E)-particle and the mature/full (F)-particle, which both exhibit low isoelectric point (pI) values but have distinct differences in infectivity and immunogenicity. Although EV-A71 particles can conventionally be separated into E-particle and F-particle using sucrose gradient ultracentrifugation, this procedure is cumbersome and difficult to put into practice for vaccine production. Methods based on ion-exchange chromatography have been exploited to improve the purification efficacy; however, none of them are capable of separating the E- and F-particles efficiently. In this study, we aimed to develop an approach to isolate and purify the highly immunogenic mature EV-A71 particles. By applying a step gradient elution procedure, we successfully isolated the viral structure protein VP0-cleaved particles of EV-A71 from a mixture of cultured viral solution using the Q-membrane anion-exchange chromatography. The elution started with 0.1x phosphate buffered saline (PBS) solution while increasing the percentage of 1x PBS containing 1M NaCl in sequential steps. By this procedure, the VP0-cleaved mature particles and VP0-uncleaved immature particles of EV-A71 could be separated into different fractions in Q-membrane with gradually increased NaCl concentration in elution buffer. The purified VP0-cleaved particles were shown to have characteristics equivalent to those of the highly infectious F-particles of EV-A71. The overall recovery rate for the mature EV-A71 particles by Q-membrane is 56% and its purity was shown to be equivalent to those isolated by the sucrose gradient ultracentrifugation. Our approach provides a simple and efficient purification method for recovering mature, highly infectious virus particles from the EV-A71 culture bulk.

Immunogenicity and Safety of an Inactivated Enterovirus 71 Vaccine Administered Simultaneously with Hepatitis B Virus Vaccine, Group A Meningococcal Polysaccharide Vaccine, Measles-Rubella Combined Vaccine and Japanese Encephalitis Vaccine: A Multi-Center, Randomized, Controlled Clinical Trial in China

Background: The aim of this study was to investigate the immunogenicity and safety of the enterovirus 71 vaccine (EV71 vaccine) administered alone or simultaneously. Methods: A multi-center, open-label, randomized controlled trial was performed involving 1080 healthy infants aged 6 months or 8 months from Shandong, Shanxi, Shaanxi, and Hunan provinces. These infants were divided into four simultaneous administration groups and EV71 vaccine separate administration group. Blood samples were collected from the infants before the first vaccination and after the completion of the vaccination. This trial was registered in the Clinical Trials Registry (NCT03519568). Results: A total of 895 were included in the per-protocol analysis. The seroconversion rates of antibodies against EV71 in four simultaneous administration groups (98.44% (189/192), 94.57% (122/129), 99.47% (187/188) and 98.45% (190/193)) were non-inferior to EV71 vaccine separate administration group (97.93% [189/193]) respectively. Fever was the most common adverse event, the pairwise comparison tests showed no difference in the incidence rate of solicited, systemic or local adverse events. Three serious adverse events related to the vaccination were reported. Conclusions: The evidence of immunogenicity and safety supports that the EV71 vaccine administered simultaneously with vaccines need to be administered during the same period of time recommended in China.

Isothermal nucleic acid amplification technology for rapid detection of virus

While the research field and industrial market of in vitro diagnosis (IVD) thrived during and post the COVID-19 pandemic, the development of isothermal nucleic acid amplification test (INAAT) based rapid diagnosis was engendered in a global wised large measure as a problem-solving exercise. This review systematically analyzed the recent advances of INAAT strategies with practical case for the real-world scenario virus detection applications. With the qualities that make INAAT systems useful for making diagnosis relevant decisions, the key performance indicators and the cost-effectiveness of enzyme-assisted methods and enzyme-free methods were compared. The modularity of nucleic acid amplification reactions that can lead to thresholding signal amplifications using INAAT reagents and their methodology design were examined, alongside the potential application with rapid test platform/device integration. Given that clinical practitioners are, by and large, unaware of many the isothermal nucleic acid test advances. This review could bridge the arcane research field of different INAAT systems and signal output modalities with end-users in clinic when choosing suitable test kits and/or methods for rapid virus detection.

A practical method for evaluating the in vivo efficacy of EVA-71 vaccine using a hSCARB2 knock-in mouse model

Hand-foot-and-mouth disease is a contagious disease common among children under 5 years old worldwide. It is caused by strains of enterovirus, especially EV-A71, which can lead to severe disease. Vaccines are the only way to fight this disease. Accordingly, it is necessary to establish an efficient and accurate methodology to evaluate vaccine efficacy in vivo. Here, we established a practical method using a hSCARB2 knock-in mouse model, which was susceptible to EV-A71 infection at 5-6 weeks of age, to directly determine the efficacy of vaccines. Unlike traditional approaches, one-week-old hSCARB2 mice were immunized twice with a licensed vaccine, with an interval of a week. The titre of antibodies was measured after 1 week. Mice at 4 weeks of age were challenged with EV-A71 intraperitoneally and intracranially, respectively. The unimmunized hSCARB2 mice displayed systemic clinical symptoms and succumbed to the disease at a rate of approximately 50%. High viral loads were detected in the lungs, brain, and muscles, accompanied by clear pathological changes. The expression of IL-1β, IL-13, IL-17, and TNF-α was significantly upregulated. By contrast, the immunized group was practically normal and indistinguishable from the control mice. These results indicate that the hSCARB2 knock-in mouse is susceptible to infection in adulthood, and the in vivo efficacy of EV-A71 vaccine could be directly evaluated in this mouse model. The method developed here may be used in the development of new vaccines against HFMD or quality control of licensed vaccines.

Analysis of the coverage of inactivated enterovirus 71 (EV71) vaccine and adverse events following immunization with the EV71 vaccine among children from 2016 to 2019 in Guangzhou

Background: Since 2016, China has approved the use of inactivated enterovirus 71 (EV71) vaccines produced by three manufacturers. The coverage and safety of different EV71 vaccines need to be evaluated.Research design and methods: The EV71 vaccination and AEFI data were collected from the Guangzhou Children's Vaccination Information Report Management System and the China AEFI Monitoring Information Management System, and the EV71 vaccine coverage rate and the AEFI incidence rate were analyzed.Results: From 2016 to 2019, the number of people who should have been vaccinated in Guangzhou was 2,781,618, and the coverage rates for doses 1 and 2 were 24.71% and 19.44%, respectively. The inoculation rates of vaccines from manufacturers A and B were between 3.03 and 10.46%. The reported incidence of AEFIs was 11.97 per 100,000 (147 cases), with fever (106 cases, 8.63 per 100,000) and allergic rash (59 cases, 4.80 per 100,000) being the most common reactions. There were no differences in the AEFI responses to the EV71 vaccines from the three manufacturers.Conclusion: The EV71 vaccines from the three manufacturers have good safety, but the EV71 vaccine coverage rate is low. It is recommended that vaccine publicity be strengthened and that the vaccine coverage rate in children be increased.

Preclinical safety assessment of a combined vaccine against Hepatitis a virus and enterovirus 71

Since 2007, Hepatitis A (HAV) vaccination has been a part of the National Immunization Program of China. Recognizing enterovirus 71 (EV71) as the most important pathogen in severe hand, foot and mouth disease, an inactivated EV71 vaccine was successfully marketed in 2015. Based on the concept of one vaccine preventing two diseases and owing to similarities in vaccine preparation and the overlap of the eligible population, a combination of the inactivated HAV vaccine and inactivated EV71 vaccine is theoretically feasible and desirable. However, the optimal vaccinationschedule for this combination vaccine has yet to be optimized. Use of this combined vaccine would not only decrease the number of vaccinations, but also lower associated cost. This study aimed to investigate the toxicity and adverse reactions of the combined HAV-EV71 vaccine under Good Laboratory Practice conditions to provide a reference for clinical studies/applications in the future. CD®(Sprague Dawley) IGS rats were employed for single-dose toxicity testing using a high dose, and repeated-dose toxicity testing using high, as well as low doses. Animals that received only a single dose showed no obvious clinical symptoms nor abnormal body weight, and no significant gross pathological change at the experimental endpoint at necropsy. In the rats injected with three doses, phagocytosis of basophilic granules by macrophages was observed in the inguinal, mesenteric, and local lymph nodes, besides irritation at the administration site. At 56 days after the last dose, no significant histopathological change was observed in the lymph nodes, and local irritation gradually faded. Further, systematic allergy testing was performed in guinea pigs. After systemic sensitization and challenge with the HAV-EV71 vaccine, animals showed normal weight gain and no allergic reactions. This study, therefore, confirmed a good safety profile of the inactivated HAV and EV71 combined vaccine.

EV71 vaccination impact on the incidence of encephalitis in patients with hand, foot and mouth disease

In order to analyze the effect of EV71 vaccination on the incidence of encephalitis in patients with HFMD, 292 cases were vaccinated, and 2,486 cases were not vaccinated which were collected in 2018 and 2019. It shows that the incidence rate of encephalitis in vaccinated patients was significantly lower than that in non-vaccinated (P = .028), which suggests that EV71 vaccine has a protective effect on the occurrence of encephalitis. But some EV71 vaccinated patients still developed into encephalitis showed that they had not produced protection or protection was weak against EV71-related encephalitis; the reasons require further investigation.